Ive not had a courtesy car, I've had a courtesy bike. Took my new (to me) Suzuki SV1000 back to the dealer for a service, since it was taking longer than expected I got a 186 mile 10 plate Honda CB1000R for the night
My mates had a few courtesy cars;
Nissan note 1.4 - We did 1000 miles in a week for a laugh, was a good car, had alot of space and cubby holes everywhere, but after we got bored and decided to ruin it by changing gear without a clutch, worked a few times before it started grinding lol
Peugoet 207 SW 1.4 - boring, slow, we tested the speakers out they were rubbish, so was the sticker asking for £35 to clean it if it was dirty, so I turned it upsidedown for lols